It is common to join together multiple components by inserting a threaded fastener, such as a screw or bolt, through aligned openings in the components and then installing a threaded nut onto the threaded fastener. Compressive force between a head of the threaded fastener and a confronting face of the nut acts to press and hold the components together. Seal-type nuts are conventionally employed to prevent fluids from flowing around the nut and into the aligned openings.
One conventional seal nut involves a cap nut attached (e.g., by crimping) to a flat washer and a concentric rubber seal bonded to a lower surface of the flat washer, as shown, for example, in FIG. 15. When this conventional seal nut is tightened against a mounting surface of a component being fastened, the bonded rubber seal becomes compressed between the flat washer and the mounting surface. In addition to providing clamping force, this compressed arrangement seals water from entering between the flat washer and the mounting surface. However, this conventional seal nut is vulnerable to losing clamping force and/or sealing ability when the rubber seal relaxes or experiences permanent compression deformation over time due to normal fatigue, environmental effects, aging, and/or exposure to variable loading. Compression deformation of the seal can allow fluid to penetrate the seal and can also result in a reduction of the clamp force exerted by the seal nut and the threaded fastener. In particular, if the seal is permanently deformed in a compressed state, a reduced amount of force will be exerted upon the components due to a reduced total thickness of the stack-up between the cap nut and the head of the threaded fastener (i.e., the stack-up comprises the components, the washer and the seal). In such circumstances, the nut must be continually and periodically manually retightened in order to restore the desired clamp force and sealing function.